The present invention relates to a variable displacement type swash plate compressor.
Japanese Patent Application Publication 2014-125993 discloses a variable displacement type swash plate compressor including a cylinder block, a front housing and a rotary shaft extending through the center of a swash plate chamber that is formed by the cylinder block and the front housing. The rotary shaft is rotatably supported by a radial bearing in the front housing. The cylinder block has therein at the center thereof a valve receiving hole in which a rotary valve is fittedly inserted. The rotary valve is mounted on the rotary shaft for rotation therewith. The rotary valve includes a small diameter portion that is press-fitted in a hole formed in the drive shaft and a large diameter portion that has therein a guide chamber. A plurality of guide holes is formed through the peripheral surface of the large diameter portion in communication with the guide chamber. The guide holes are spaced at 180 degree interval in the circumferential direction of the rotary valve. The guide chamber and the guide holes of the rotary valve cooperate to form a rotary valve passage. The rotary valve passage is connected to communication passages which are connected to cylinder bores successively with the rotation of the rotary valve. The communication passages are connected to the guide chamber through the guide holes.
According to the compressor of the above-cited publication, blowby gas leaking from one of compression chambers is guided through an annular groove, a straight groove, a communication passage and the guide hole and stored in the guide chamber temporarily. The blowby gas is flowed through the guide hole and another communication passage into another compression chamber for collection of refrigerant gas. Such structure is adaptable to various displacement and may effectively reduce blowby gas leaking into the swash plate chamber at various displacement of the compressor.
Japanese Patent Application Publication 2015-68187 discloses another variable displacement type swash plate compressor that has a collection-and-supply mechanism. The collection-and-supply mechanism includes a plurality of collection passages, a plurality of supply passages, an annular space, an inlet port and an outlet port. The inlet port is communicable with one of the collection passages which is working actually at the time. The outlet port is communicable with one of the collection passages which is working at the time. In this compressor, when the inclination angle of the swash plate is at the maximum, the residual refrigerant gas in the compression chamber is collected by the working collection passage and then is supplied to the other compression chamber. In this compressor, however, the supply of the residual refrigerant gas to the other compression chamber does not take place when the inclination angle of the swash plate is less than the maximum.
According to the compressor disclosed in the publication 2014-125993, there is a fear that noise occurs by the effect of the pressure waveform in the cylinder bore, though the blowby gas leaking out from one compression chamber may be collected by another compression chamber in the intermediate displacement operation. Additionally, collection of blowby gas may heat suction gas thereby to increase the power required for compression, with the result that the coefficient of performance (COP) of the compressor may be deteriorated.
According to the compressor disclosed in the publication 2015-68187, on the other hand, noise is not generated by effect of the pressure waveform because the residual refrigerant gas is not supplied to the other compression chamber when the inclination angle of the swash plate is less than the maximum. However, there is a fear that refrigerant gas in the working collection passage may leak between the piston and the cylinder block into a crank chamber (control pressure chamber) because the connection between the working collection passage and the other compression chamber is shut off when the inclination angle of the swash plate is less than the maximum. In order to prevent the leakage of the refrigerant gas, hermeticity between the piston and the cylinder bore needs to be enhanced.
The present invention, which has been made in light of the above-described problems, is directed to providing a variable displacement type swash plate compressor that can prevent noise and leakage of a refrigerant gas from a cylinder bore to a control pressure chamber when the displacement of the compressor is changed.